feat: enhance backend security and configuration

- Updated Dockerfile to improve security with a non-root user and added health checks.
- Modified docker-compose.yml to set containers as read-only, restrict ports to localhost, and implement health checks.
- Enhanced .env.example with additional environment variables for security and configuration.
- Improved FastAPI application with middleware for security headers, CORS, and body size limits.
- Refactored authentication flow in auth.py to include state validation and improved error handling.
- Added rate limiting to various endpoints to prevent abuse.
- Updated researcher and publication handling to ensure better validation and error management.

backend/app/scheduler/sync_scheduler.py

@@ -9,9 +9,16 @@ import os
 # Cargar variables del .env
 load_dotenv()
 
+# ---------------------------------------------------------
+# Variables de entorno
+# ---------------------------------------------------------
+
 API_KEY = os.getenv("API_KEY_VALUE")
 BASE_URL = os.getenv("BASE_URL")
 
+# ---------------------------------------------------------
+# Función auxiliar: ejecutar sincronización mensual
+# ---------------------------------------------------------
 
 def run_monthly_sync():
     db = SessionLocal()
@@ -36,6 +43,9 @@ def run_monthly_sync():
 
     db.close()
 
+# ---------------------------------------------------------
+# Función auxiliar: iniciar el scheduler
+# ---------------------------------------------------------
 
 def start_scheduler():
     scheduler = BackgroundScheduler()